Actuating tool

ABSTRACT

The invention relates to an actuating tool for a fastener having an internal polygon arrangement, particularly a screw, with a tool head having an external polygon arrangement to fit into this internal polygon arrangement, wherein the tool head has a circumferential recess to receive a spring washer. It is provided that the width of the recess ( 17 ) is greater than the dimension of the spring washer ( 21 ) measured in the direction of the width, and the spring washer ( 21 ) is elastically supported at least in partial areas against the sidewalls ( 41, 43 ) of the recess ( 17 ).

The invention relates to an actuating tool for a fastener having aninternal polygon arrangement in accordance with the preamble of claim 1.

An actuating tool of the initially described type is known from GermanPatent DE-PS 44 16 268. It serves to screw in or unscrew hexagon socketscrews. For this purpose, the tool is provided with a hexagon socketinsert bit that fits into the hexagon socket of the screw. In aninsertion element that is provided with the hexagon socket insert bit,an elastic clamping device is arranged, which is accommodated in arecess of the insertion element. When the tool is inserted into thehexagon socket, a force is applied to the clamping arrangement designedas a snap ring. The beveled open ends of the snap ring thereby movetoward each other so that the outside diameter of the ring is reduced.This allows the insertion element to slide into the hexagon socket ofthe screw. The disadvantage of this prior-art actuating tool is that thesnap ring can very easily slip within the recess, which in many casesmakes it impossible to insert the tool into the hexagon socket. Afurther disadvantage is that the snap ring is compressed in such a waythat the bevels of the ends do not project above the edge of the recessso that a secure hold of the tool within the hexagon socket is notensured in all cases.

German Utility Model 297 08 764 discloses a screwdriver with a polygonalengagement area. It is provided with a recess into which a plastic ringis inserted, which is elastically deformed when the tool is pushed intothe internal polygon arrangement of a screw. Another embodiment of thescrewdriver provides for a spring washer with a rosette-like contour tobe inserted into the recess, whereby the areas between its rounded edgesare curved. With frequent use, however, such clamping elements wearquickly, particularly the plastic ring. The spring washer with therosette-type contour is complex and costly to produce.

Thus, the object of the invention is to create an actuating tool for afastener with an internal polygon arrangement, which obviates theinitially described disadvantages.

This object is attained by means of an actuating tool with the featurescited in claim 1. The tool is distinguished, in particular, in that arecess for a spring washer is made in a tool head with an externalpolygon arrangement, that the spring washer is in partial areaselastically supported against sidewalls of the recess and in its no-loadstate projects above at least one, preferably above each face of theexternal polygon arrangement, and that the depth of the recess isgreater than or equal to the dimension of the spring washer measured inthe direction of the depth. The elastic support advantageously ensuresthat the spring washer is centered when the tool head is first insertedinto an internal polygon arrangement of a screw and that it retains thisposition after the tool is withdrawn from the screw. Thus, the springwasher is fixed or braced by the elastic support within the recess.Consequently, the insertion force during subsequent insertion processesremains nearly constant since the limiting edges of the internal polygonarrangement strike substantially the same position of the spring washerwhen the tool is inserted. As a result, the force is transmitted fromthe limiting edges to the spring washer at substantially always the sametangent angle. The actuating tool according to the invention is thusdistinguished by the fact that the spring washer cannot slipuncontrollably within the recess, which ensures simple and secureinsertion of the tool at a nearly constant insertion force. Since thespring washer in its no-load state projects above at least one,preferably above each flat face of the external polygon arrangement,constant forces act on the spring washer from each flat face of theinternal polygon arrangement when the tool is inserted. The fact thatthe depth of the recess is equal to or greater than the dimension of thespring washer measured in the direction of the depth ensures that thespring washer is completely received by the recess when a force isapplied.

A preferred embodiment provides that the spring washer forms a turn inthe manner of a helical spring. In other words, the spring washer iscrossed, with the opposite ends of the preferably open spring washerbeing laterally offset. Through this crossing of the spring washer, theturn of which thus extends along an imaginary helix, said spring washeris at least in partial areas elastically supported against the sidewallsof the recess. This ensures secure positioning of the spring washerwithin the recess. In a preferred embodiment, the recess extends in aplane, whereby a normal of said plane coincides with a longitudinal axisof the actuating tool. The spring washer thus extends in a concentriccircular path around the longitudinal axis of the tool.

Furthermore, it is preferably provided that the ends of the open springwasher nearly touch each other in their loaded state. A nearly closedspring washer is thus formed, which is elastically supported against theflat faces of the internal polygon arrangement. This achieves a securehold of the tool within the screw.

Furthermore, it is preferably provided that the recess is formed as asubstantially rectangular or U-shaped groove. Consequently, the crossedspring washer can at least in partial areas be supported against thesides of the groove. Thus, it retains its position with respect to thelongitudinal axis of the tool.

A particularly preferred embodiment provides that the spring washer isformed by preferably a spring-hard wire, which can have a substantiallycircular cross section. Alternatively, it may be provided that thespring washer has an angular cross section, which is preferablytriangular, rectangular or hexagonal. The cross section may also betrapezoidal. An angular cross section has the particular advantage thata diagonal face of the spring washer meets the limiting edges of theinternal polygon arrangement. This causes substantially equal forces toact during insertion, since the limiting edges meet the diagonal tocreate a radial force component that pushes the spring washer into therecess. This is particularly advantageous if the dimensions of the tooland/or the internal polygon arrangement of the screw have tolerances.

A preferred embodiment provides that the diameter of the cross sectionof the spring washer be 0.07 to 0.14 times the width across flatsdefined by the polygon arrangement.

In a particularly preferred embodiment, the actuating tool isdistinguished by the fact that the tool head is formed by two sphericalsegments, that their bases are facing each other and are spaced at adistance from each other, and that their center points—measured in thedirection of the longitudinal axis of the actuating tool—are preferablyspaced a distance from each other. Thus, a spherical head is formed,which comprises two halves of a sphere, has the dimensions of theexternal polygon arrangement, and permits insertion of the actuatingtool into the internal polygon arrangement even if the longitudinal axisof the actuating tool is not aligned with the longitudinal axis of thescrew. This is particularly advantageous if the screw is located behindan obstacle. Furthermore, it is provided that the center point of thefirst spherical segment and the center point of the second sphericalsegment are located along the longitudinal axis of the actuating tooland that the center points are located within a space between the basesof the spherical segments.

A particularly preferred embodiment provides that one spherical segmentof the spherical head is arranged on a shank of the actuating tool, andthat on the other spherical segment a truncated cone is preferablyattached whose lateral surface forms an angle α with the normal, i.e.the longitudinal axis of the actuating tool. Furthermore, it ispreferably provided that the center axis of the truncated cone coincideswith the longitudinal axis of the actuating tool. The truncated coneattached to the spherical segment forms an insertion area of the tool,which on the one hand limits a pivoting angle of the actuating tool withrespect to the longitudinal axis of the screws. On the other hand, italso prevents the tool head from being inserted into the internalpolygon arrangement of the screw if the pivoting angle was selected toolarge. This prevents damage to the screw or the tool. Specifically, themaximum permissible pivoting angle can be 3° to 40°, preferably 30°.Thus, it is provided that the lateral surface forms a 30° angle with thenormal, i.e. the longitudinal axis of the actuating tool.

Finally, a preferred exemplary embodiment provides that the truncatedcone has an external polygon arrangement on its lateral surface, wherebythe external polygon arrangement of the tool head merges into thepolygon arrangement of the truncated cone. This ensures that, if theactuating tool is pivoted, a force transmission is possible also via thepolygon arrangement of the truncated cone. Moreover, at least two facesof the polygon arrangement of the truncated cone contact the oppositeflat faces of the internal polygon arrangement when the maximum pivotingangle is reached. Thus, said faces lie on top of each other and therebyprevent impermissibly high surface pressures, so that neither the screwnor the actuating tool is damaged.

Additional advantageous embodiments are set forth in the subclaims.

Below, the invention is explained in further detail by means of thedrawing. The following show:

FIG. 1 a perspective view of a tool head of an actuating tool,

FIG. 2 a section through the tool head of FIG. 1,

FIG. 3 a spring washer,

FIG. 4 the tool head according to FIG. 1 in a side elevation,

FIG. 5 a section through the tool head parallel to the longitudinal axisof the actuating tool, and

FIGS. 6a to 6 d various embodiments of the spring washer.

Below, purely by way of example, an actuating tool is assumed to berealized, particularly a socket screw wrench for a fastener with aninternal hexagon socket arrangement, particularly a hexagon socketscrew. This internal polygon arrangement can of course also have adifferent number of corners. It is furthermore assumed, purely by way ofexample, that the actuating tool has a spherical-type tool head. Thetool head may of course also be made in the form of a cylinder.

FIG. 1 depicts an actuating tool 1. This tool essentially comprises acylindrical hexagon shank 3, which at its one end is provided with atool head 5. This tool head 5 is made as a spherical hexagon head withan external hexagon arrangement 7. Hexagon tool head 5 is integrallyformed with shank 3, whereby shank 3 comprises beveled faces 9 thatslope toward a center axis of the tool so as to form a constriction 11.In the area of constriction 11, tool head 5 adjoins with faces 13, whichincrease toward an end 15 of tool head 5, i.e. their distance to thelongitudinal axis of actuating tool 1 increases. In the further courseof tool head 5, a recess 17 is provided, which is realized as asubstantially rectangular or U-shaped groove 19, also referred to asneck. In the area between constriction 11 and groove 19, tool head 5 isformed by a first spherical segment 20. Groove 19 accommodates a springwasher 21. In the further course of the tool head, toward end 15,outwardly curved faces 23 sloping toward the center axis of actuatingtool 1 adjoin groove 19. Faces 23 are the outer faces of a secondspherical segment 25 of tool head 5 to which a truncated cone 27 isattached. Said truncated cone 27 with its truncated face 29 forms theend 15 of the actuating tool 1. The truncated cone, along its lateralsurface 31, is provided with a polygon arrangement, particularly ahexagon arrangement 33. It is clearly apparent from FIG. 1 that theexternal hexagon arrangement 7, or tool head 5, is formed by the firstspherical segment 20, the second spherical segment 25, and the truncatedcone 27. In other words, faces 13 of the first spherical segment 14,faces 23 of the second spherical segment 25, and the lateral surface 31each merge into each other.

FIG. 2 depicts an enlarged sectional view of tool head 5. It is readilyapparent that the preferably open spring washer 21 is arranged in groove19. It is spaced at a distance from a groove bottom 35 of groove 19.Depth t of recess 17 or groove 19 is selected in such a way that springwasher 21, the cross section of which has a diameter d, can becompletely accommodated by groove 19 in its loaded state. “Loaded state”in terms of the application means that a force is applied from theoutside to spring washer 21 along its lateral surface 36, which pushesit or its ends 37 and 37′ together. It is readily apparent that springwasher 21 projects above faces 13 and faces 23 (FIG. 4). The open springwasher 21 has an opening gap 39 whose width b is selected such that whena force is applied to spring washer 21, its outside diameter A isreduced so that it is completely accommodated by groove 19 or recess 17.Its ends 37 and 37′ are thereby displaced toward each other such thatthe spring washer is nearly closed, i.e. ends 37 and 37′ almost toucheach other. The fact that there is a small distance between ends 37 and37′ in their loaded state provides for some residual elasticity, whichpermits ends 37 and 37′ to move further toward each other. This may berequired, for example, if actuating tool 1 is pivoted in relation to ascrew. Ends 37 and 37′ of spring washer 21 are preferably made withsharp edges and without burrs so that they form flat cross-sectionalfaces that nearly touch each other when spring washer 21 is loaded. FIG.2 furthermore depicts a width across flats SW that is defined by adistance between two diametrically opposite faces. Diameter d of springwasher 21 preferably is 0.07 to 0.14 times the width across flats SW.

FIG. 3 is a side view of spring washer 21. It shows that spring washer21 has a turn W that follows an imaginary helix. As a result, ends 37and 37′ are not directly opposite but laterally offset with respect toeach other. Spring washer 21 is thus crossed such that it is elasticallysupported against sidewalls 41 and 43 with its lateral surface 36 (FIG.4). However, spring washer 21 can also have an undulating design, toprovide a quasi wave-shaped spring washer. Finally, a crossed springwasher 21 can have an undulating design as well.

FIG. 4 schematically shows actuating tool 1 in a side elevation, inwhich the polygon arrangement has been omitted for the sake of clarity.It may be seen that spring washer 21 is centered with respect to alongitudinal axis 45 of actuating tool 1, whereby spring washer 21 isshown in its no-load state, i.e., spaced at a distance from groovebottom 35. FIG. 4 clearly shows that tool head 5 is formed by sphericalsegments 20 and 25 and truncated cone 27. It also clearly shows thatrecess 17 extends in plane E1, with a normal of said plane E1 coincidingwith longitudinal axis 45. In other respects, identical parts areidentified by the same symbols as in FIG. 1; to that extent reference ismade to their description.

FIG. 5 is a sectional view of actuating tool 1, whereby longitudinalaxis 45 is located in the sectional plane. Parts that are identical tothose in FIGS. 1 to 4 are identified by the same symbols; to that extentthey are not re-described here. FIG. 5 again shows that tool head 5 isformed by the first and second spherical segment 20 and 25 and truncatedcone 27. The bases of the first and second spherical segments 20 and 25are facing each other and are preferably arranged so that they arespaced at a distance x from each other reflecting the width of recess 17or groove 19. A center point M 1 of the first spherical segment 14 and acenter point M 2 of the second spherical segment 25 are located at adistance from each other along longitudinal axis 45 of actuating tool 1within a space between the bases of spherical segments 20 and 25.Diameter r of the first and second spherical segment 20 and 25 ispreferably slightly larger than half the width across flats SW. In otherwords, the largest diameter of the tool head, which corresponds to thewidth across flats SW of the polygon arrangement, is reached at thejunction between sidewall 41 of groove 19 and face 23 of the secondspherical segment 25.

If the actuating tool is to be used at an angle with respect to the axisof the screw (not depicted), the width across flats SW of the polygonarrangement is formed by faces 13 and 23. In other words, the distancebetween two diametrically opposite faces 13 and 23 corresponds to twicethe radius r and defines the width across flats SW if actuating tool1—as previously mentioned—is to be inserted at a pivoting angle into theinternal polygon arrangement of the screw. The maximum pivoting angle ofthe actuating tool 1 in relation to the screw is determined by angle αformed by the lateral surface 31 of the truncated cone 27 with centralaxis 45. Specifically, this angle α can be 30° to 40°, in this caseapproximately 30°. Angle α thus determines the maximum permissiblepivoting range of actuating tool 1 in relation to the screw. In otherwords, if tool head 5 is inserted into the internal polygon arrangement,actuating tool 1 can be pivoted until one face of hexagon arrangement 33abuts against a side face of the internal polygon arrangement. DimensionM of the constriction must be adapted to angle α, i.e., the diameter ofconstriction 11 must be dimensioned such that at the maximum pivotingangle, contact between actuating tool 1 in the area of constriction 11and a screw is prevented. If tool head 5 is to be inserted into theinternal hexagon arrangement of the screw at a pivoting angle greaterthan the maximum permissible pivoting angle, the attached truncated cone27 prevents tool head 5 from being inserted into the screw. This isachieved in that the longitudinal extension of truncated cone 27 isselected such that at least one limiting edge of the internal polygonarrangement of the screw meets truncated face 29, or a transitional edge47 between lateral surface 31 and truncated face 29 is wedged with aninterior surface of the screw, since a distance of transitional edge 47to a face 13 is greater than the width across flats SW. Truncated cone27 thus forms an insertion area of actuating tool 1, which limits thepivoting angle and thus prevents damage to the screw and to tool head 5.

FIGS. 6a to 6 d each show detail views of a tool head 5 of an actuatingtool 1, which is distinguished from the exemplary embodiment discussedabove only by different embodiments of the spring washer. FIG. 6adepicts a spring washer 21′ the cross section of which is substantiallytriangular. FIG. 6b shows a substantially hexagonal spring washer 21″,FIG. 6c a substantially trapezoidal spring washer 21′″ and FIG. 6d asubstantially rhombic spring washer 21″″ in cross section. Aparticularly advantageous feature in these embodiments is that adiagonal S of spring washer 21′, 21″, 21′″, and 21″″ contacts a limitingedge of an internal polygon arrangement of a screw. The insertion forceto be applied can be varied through the angle of the diagonal S withrespect to longitudinal central axis 45. Due to the fact that thisdiagonal S is provided, when the spring washer meets the limiting edgeof the internal polygon arrangement, a force component is produced,which radially acts on the spring washer to move the spring washerradially inwardly. Since a constant angle is present across the entirecourse of diagonal S, any insertion force to be applied is in all casesconstant. To that extent, these spring washers are advantageous comparedto round spring washers. The latter are distinguished by a variableinsertion force.

Based on the above, it is readily apparent that tool head 5 can also beimplemented without a truncated cone 27. In this case, too, optimalholding properties of spring washer 21 are realized. Thus, limiting thepivoting range of the actuating tool by means of the truncated cone 27provides the additional advantage that at the maximum possible pivotingangle the spring washer remains engaged with the internal polygonarrangement and ensures a secure hold. It is also possible, however, toprovide a spring washer for an actuating tool with a cylindrical toolhead, which has a secure hold in engagement position with a screw and,furthermore, requires a nearly constant insertion force with eachinsertion process.

What is claimed is:
 1. An actuating tool for a fastener having aninternal polygon arrangement, the actuating tool comprising: a tool headhaving a first generally hemispherical segment and a second generallyhemispherical segment defining a spherical head having an externalpolygon arrangement for nesting in the internal polygon arrangement ofthe fastener, and a circumferential recess for receiving a springwasher, the circumferential recess having sidewalls and being disposedbetween the first and second generally hemispherical segments; and aspring washer disposed in the circumferential recess; wherein the widthof the recess is greater than the depth of the spring washer, andwherein the sidewalls of the recess at least partially support thewasher.
 2. The actuating tool according to claim 1, wherein the firstgenerally hemispherical segment and the second generally hemisphericalsegment each have a base, and wherein the bases face each other and aredisposed adjacent the recess.
 3. The actuating tool according to claim1, wherein the spring washer is open and wherein the spring washerdefines a generally helical turn.
 4. The actuating tool according toclaim 1, wherein the actuating tool has a longitudinal access andwherein the recess of the tool head extends in a plane normal to thelongitudinal axis of the actuating tool.
 5. The actuating tool accordingto claim 1, wherein the first generally hemispherical segment and thesecond generally hemispherical segment has a cross-sectional shape whichis polygonal.
 6. The actuating tool according to claim 5, wherein thecross-sectional shape is triangular, rectangular or hexagonal.
 7. Theactuating tool according to claim 5, wherein the cross-sectional shapeis trapezoidal.
 8. The actuating tool according to claim 5, wherein thecross-sectional shape is rhombic.
 9. The actuating tool according toclaim 1, wherein the spring washer has a diameter, the first generallyhemispherical segment and the second generally hemispherical segmenthave opposing flat surfaces spaced apart at a distance, and wherein thediameter of the spring washer is between 0.07 to 0.14 times the distancebetween the opposing flat surfaces.
 10. The actuating tool according toclaim 1, wherein the first generally hemispherical segment and thesecond generally hemispherical segment each have a center point, andwherein the center point of the first generally hemispherical segment isspaced apart from the second generally hemispherical segment.
 11. Theactuating tool according to claim 1, wherein the first generallyhemispherical segment and the second generally hemispherical segmentform a generally hemispherical head on a shank of an actuating tool. 12.The actuating tool according to claim 1, wherein one of the generallyhemispherical segments comprises a truncated cone attached thereto, thetruncated cone having lateral surfaces disposed at an angle ofapproximately 30 degrees relative to a longitudinal axis of theactuating tool.
 13. The actuating tool according to claim 12, whereinthe truncated cone has a polygon arrangement along its lateral surface.14. The actuating tool according to claim 13, wherein the externalpolygon arrangement defines a hexagon.
 15. An actuating tool forengaging and rotating a fastener, the actuating tool comprising: a toolhead having a first generally hemispherical segment defined by aplurality of generally flat surfaces and a second generallyhemispherical segment defined by a plurality of generally flat surfaces,and a circumferential recess disposed between the first and secondgenerally hemispherical segments for receiving a spring washer; and aspring washer disposed in the circumferential recess; wherein the springwasher is not continuous and is formed with a generally helical wind;and wherein the recess in the tool head is sufficiently deep that thespring washer may completely nest inside the recess.
 16. The actuatingtool according to claim 15, wherein the tool head has a rounded portionbetween the generally flat surfaces of the first generally hemisphericalsegment and the second generally hemispherical segment, and wherein therecess is formed in the rounded portion.
 17. The actuating toolaccording to claim 16, wherein the second generally hemisphericalsegment comprises a single hexagonal truncated cone.
 18. The actuatingtool according to claim 17, wherein the actuating tool has alongitudinal axis, and wherein the second generally hemisphericalsegment has a rounded portion and an end and a plurality of generallyflat faces, each of the plurality of generally flat faces extending fromthe rounded portion to the end and being disposed at an angle of betweenabout 30 degrees and 40 degrees relative to the longitudinal axis of theactuating tool.
 19. The actuating tool according to claim 18, whereinthe second hemispherical segment comprises a single hexagonal truncatedcone.
 20. The actuating tool according to claim 18, wherein the end ofthe second hemispherical segment is flat and normal to the longitudinalaxis of the actuating tool.
 21. The actuating tool according to claim15, wherein the width of the recess is greater than the depth of thespring washer.